Many of us learned first genetics lessons through peas and eye color. But there is more science when Explain the color that acquire our eyes. Not only does physics intervene but also a somewhat more complex biology than we believed in the beginning.
Nature and blue. The blue color It is not one of the most frequent In nature. Perhaps that is why exceptions such as the flowers of this color, the plumages of some birds or the wings of certain insects are striking.
A reason is in the optimization of resources. Blue pigments are molecules that reflect light in certain segments of the electromagnetic spectrum, those of blue tones, giving color to an object.
The problem with these molecules is that They usually have a large size. This makes them difficult to synthesize by living beings so, if they do not offer a significant evolutionary advantage, they will not be created by our body.
It is not chemical, it is physical. That is why when we see the blue color in nature, it is likely that its origin is not in a chemical compound but in some physical phenomenon. This is what happens, for example, in the case of the plumage of some birds, whose origin is in nanostructures whose shape is responsible for reflecting the light in short lengths of the visible spectrum, those of blue color. And it is also the case with blue eyes.
Absence of pigmentation. Only that in the case of blue eyes it is not about the nanostructures but of the iris and of the Tyndall effectan effect similar to the person responsible for seeing the blue sky (and the red sunsets), Explain in an article in The conversation Davinia Beaver, expert in regenerative medicine of the Bond University, in Australia.
When the light enters our eye, the suspended particles found in it interact with the shortest spectrum lengths, causing them to disseminate more, “bouncing” thus part of the blue color of the waves outside.
The brown, quite the opposite. This effect does not occur among people with brown eyes because there is a pigment in this. This “catch” part of the light causing it not to escape so easily from the eye, giving darker tones. The pigment in question: melaninthe same responsible for darker skin tones.
There are more eyes colors, such as green or “hazelnut color” eyes. These colors can be seen as the combination of the dispersion of the light of the Tyndall effect, modulated by a certain presence of melanin, either in small quantities or concentrated in some regions of the iris.
Genetics is not so simple. The genetics we study in our school stage, of course, is simple, a simplified version of what we know about this field of biology. A field, in addition, that has been advancing over time, becoming more complex as we detract more and more details about its operation, Beaver remembers. Point out, for example, there are several genes that affect the appearance of our eyes, so family ins and outs that lead to one or another eye color may not be as perceptible as we believe.
Eye color can also change as a result of other factors such as our age, as melanin accumulates in our eyes, which usually happens during growth. Certain medical conditions, Beaver adds, can also influence this color.
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Image | Michael Morse
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